SURGING HISTORY AND POTENTIAL FOR RENEWED RETREAT - BERING GLACIER, ALASKA USA

Citation
Eh. Muller et Pj. Fleisher, SURGING HISTORY AND POTENTIAL FOR RENEWED RETREAT - BERING GLACIER, ALASKA USA, Arctic and alpine research, 27(1), 1995, pp. 81-88
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geografhy
Journal title
ISSN journal
0004-0851
Volume
27
Issue
1
Year of publication
1995
Pages
81 - 88
Database
ISI
SICI code
0004-0851(1995)27:1<81:SHAPFR>2.0.ZU;2-5
Abstract
Late Wisconsinan glacial recession uncovered a fiord where now Bering Glacier descends to the Gulf of Alaska coast. At maximum extent in the early Holocene, the fiord may have reached 50 km inland. Gradual glac ial readvance may have begun by 6000 yr BP. At least by 4500 yr BP, an d throughout the latter part of this advance, the glacier margin was p rotected against calving by its own sediment apron. Rhythmically invol uted medial debris bands record frequent surging in previous centuries and perhaps throughout Neoglacial history. Air photos document surges that culminated about 1940, 1960, and 1968. An hypothesis of 20 to 30 yr surge cyclicity is strengthened by current activity. Between 1968 and 1993, retreat of 2 to 5 km on the east flank of the piedmont lobe exposed buried forest beds and outwash. Basins, eroded in this drift s equence primarily by glacial action, now contain proglacial lakes 50 t o 80 m or more in depth. Continued ice recession at recent rates would , within a few years, have caused these several lakes to join as a sin gle lake temporarily retained a few meters above sea level by an unlit hified sediment barrier. Glacier retreat into deeper water, and exposu re to tidal activity would have induced more active calving were it no t for the surge which began in spring 1993. However, unless the curren t advance is unusually vigorous, it will only temporarily interrupt ra ther than completely reverse the recent long-term trend toward retreat .